/Engine/Source/Runtime/Engine/Public/MaterialShared.h
Tracks FMaterials without a correspondingUMaterialInterfacein the editor, for example FExpressionPreviews. Used to handle the 'recompileshaders changed' command in the editor. This doesn't have to use a reference counted pointer because materials are removed on destruction.
static [TSet](API\Runtime\Core\Containers\TSet)< [FMaterial](API\Runtime\Engine\FMaterial) * > EditorLoadedMaterialResources;